Imagine running with 60 pounds of gear up a few flights of stairs in a burning building, heaving a 150-pound unconscious person over your shoulder and running back down, all in a matter of minutes.

Sound hard? Welcome to the world of your typical firefighter-paramedic. These public safety personnel, like their counterparts in law enforcement and the military, have to be in top shape. They probably can't go head to head with an elite triathlete in an Ironman event or play offensive line for the Tampa Bay Buccaneers. But in a crisis, the public safety generalists are a whole lot more useful than the athlete specialists.

Welcome to the world of CrossFit, a workout that develops the skills that generalists prize.

"We have to be ready for anything," said Shaun Carroll, a 28-year-old Largo firefighter. "That is why this exercise program is so valuable. It prepares you for life."

Carroll and two of his fellow first responders, Kyle Lighthiser and Alex Cottom, got tired of traditional gyms and the same old routines. So they opened their own CrossFit center in a Largo industrial park in December.

"It is like P90X and boot camp turned on its head," said Lighthiser, 27, referring to two other popular workout regimens.

"It's functional movements performed at a high intensity in a group setting under supervised coaching.''

No frills

Don't expect fancy machines, mirrored walls or even air-conditioning when you step into the CrossFit Tampa Bay "box,'' as these no-frills facilities are known. It is outfitted with just weights, mats, ropes and rings — and that turns out to be all the gear that's needed.

"A lot of our exercises use your own body weight," said Cottom, 28, a former wrestler and football player who adopted CrossFit after lifting weights got old. "Everybody does the same thing, but they proceed at their own pace, and because it is a group setting, you always have somebody urging you on."

The CrossFit craze was started in California in 1995 by a former gymnast, Greg Glassman. The idea was to develop a "functional" exercise routine that would benefit real people in their everyday lives.

The system, which relies heavily on moves you probably learned in school gym class — squats, lunges, pushups and pullups — became a hit with everybody from SWAT team members to Navy SEALs.

Now there are more than 3,000 CrossFit gyms worldwide and more than a couple dozen in the Tampa Bay area. (Find one near you at crossfit.com).

Each adheres to the same basic format, the core of which is the infamous WOD, or "workout of the day."

Walk into any CrossFit box and you'll likely see it posted on the wall.

"People love it," Cottom said. "You can be in and out of here in less than an hour. It can really be a life-changing experience."

Safety concerns

CrossFit, like any intense physical activity, is not without risk. Jump into any routine without the proper buildup and you can be injured, or so sore that you won't go back for another workout. That's why trainers recommend starting slowly and building strength and endurance over time.

Most CrossFit routines are designed to be performed until you reach "muscle failure'' — that point when you absolutely cannot do one more repetition.

So it is important to know your limits. To receive the maximum benefits from exercise you need to push yourself, and should plan on working out at least three times a week and even more for maximum results.

But you also need to know when to stop. If you have an addictive personality and tend to overdo, CrossFit may not be the program for you.

The program has been associated with a rare condition known as rhabdomyolysis, which occurs when muscle fibers break down and release a protein called myoglobin into the bloodstream, potentially leading to severe kidney damage. But "rhabdo" can affect any athlete who pushes too hard.

As with any exercise program, moderate, steady consistency is the key. To get results, you have to stick with it. A good CrossFit box will let you proceed at your own pace.

If you haven't worked out in a long time, and particularly if you have a history of health problems, talk to your doctor before starting CrossFit or any vigorous routine.

Posted on the wall, the daily routine often is named for former CrossFitters who were killed in the line of duty. The hero's story is read before every workout to memorialize and motivate.

On Wednesday, the workout on the board at CrossFit Tampa Bay in Largo was named for Navy Special Warfare Operator Chief Colin Trent Thomas, 33, of Morehead, Ky. Assigned to a Navy SEAL team based in Little Creek, Va., he was fatally shot on Aug. 18, 2010, during combat in eastern Afghanistan. He is survived by his fiancee, Sarah Saunders, his parents, Clay and Jean Thomas, and his sister, Meghan Edwards.